Here's a generic build order for a rush.
Peon 1: Town Hall
Peon 1: Farm
Peon 1: Barracks
Peon 2: Farm (Peon 2 stays on continuous farm production)
Peon 3: Blacksmith
Peon 4: Barracks
Peon 5 and on wards start mining gold, and after each barracks and your blacksmith finish send those peons to gold as well.
You will not be mining enough gold to pump 2 grunts and a peon every macro cycle so you need to choose based on what's happening in the game what you need more. A lot of people are scared to stop peon production momentarily due to falling behind economically but if you are able to deal damage with your units you can make up for the slight economic setback tenfold. If you have an enemy at the spot next to you just halt peon production entirely and stop making farms when you have 17 food (4 farms). Pump grunts out and when you get 4 start heading to the enemy base and don't forget to rally the next 2 to your group of 4 and drop another farm and don't forget level 3 (crucial). Control grouping your armies helps a lot in this regard. Now let's say for instance you don't have a neighbor and your ally doesn't need immediate help. If that's the case you want to rush out 3 grunts to scout together, but not giving up peon/farm production whatsoever. This will give you an economic lead and the ability to utilize both of your barracks at the same time to produce grunts in macro cycles. You want to be vigilant in your scouting, produce grunts out of 1 of the barracks, and begin to form a choke or funnel at the entrance to your base until you are able to sustain both barracks. Once you get to around 21 food you should be at that point. At some point you're going to want to start chopping lumber. Generally when you reach 950 wood you will want to send a peon or two to start chopping to keep up with continuous farms and levels. You will have to assess the game and decide if you can deal damage with early units, and if continuing upgrading past level 3 is worth it. If you decide it's not, then you begin dropping your lumber mill and pulling more peons to chop lumber and begin the transition to teching up to tier 2. It is very important if you are halting grunt production in order to tech to keep a scout close to your opponents base to keep an eye on what he is up too. The sooner you find out, the sooner you can start reacting and countering it. Now my recommendation for a newer player is to focus entirely on the early game because that phase is much easier to compete in then later on. Focus on making a solid grunt army with at least level 4, and work on trying to use them to deal damage and delay your enemies. Once you master the rush you will be able to have a lot of fun in big team games!